Do you think governments are afraid legalizing bitcoin because it's difficult regulating its use, circulation, determining individual's worth, earnings and may lead to tax evasion?
I don't think they are "afraid" (well, we can talk about all governments in one). I believe there is general interest in trying to determinate the legal situation of bitcoin, but is going to take a while. It is not easy to determinate how new "money" is going to fit into the economic system of a country. It takes a lot of bureaucracy, and maybe is going to take more than a few years.